Conventionally, a solid-state image sensor such as a charge coupled device (CCD)/complementary metal oxide semiconductor (CMOS) image sensor is used, for example, in an electronic device having an imaging function such as a digital still camera and a digital video camera.
For example, incident light incident on the CMOS image sensor is subjected to photoelectric conversion by a photodiode (PD) being a photoelectric converting unit included in a pixel. Then, an electric charge generated by the PD is transferred to floating diffusion (FD) through a transfer transistor and an amplification transistor outputs a pixel signal of a level according to the electric charge accumulated in the FD.
In a conventional solid-state image sensor, there is a case in which the light incident on the solid-state image sensor is reflected therein and flare and ghost occur by the reflected light imaged in an image. For example, the light reflected by an on-chip lens and a silicon surface of the pixel of each color is reflected by a seal glass surface and an infrared radiation cutoff filter surface to be incident again on the photoelectric converting unit and the flare occurs. Also, for example, red light reflected by the silicon surface of the red pixel and the on-chip lens surface is reflected by a multicoated surface of the infrared radiation cutoff filter to be incident again on the photoelectric converting unit and the ghost which looks like a red ball occurs.
In order to prevent such reflection of the light on the silicon surface to decrease the occurrence of the flare and ghost, a structure in which a fine uneven structure is periodically arranged, a so-called moth-eye structure is known. In the moth-eye structure, a refractive index gradually changes, so that reflectivity may be decreased.
For example, Patent Document 1 suggests the so-called moth-eye structure in which the fine uneven structure is formed on an interface on a side of a light receiving surface of a silicon layer in which the photodiode is formed as the structure of preventing the reflection of the incident light.